Initializing `json` by direct initialization and copy initialization invokes different constructors

[FeignClaims]

Description

• direct initialization demo

  #include <iostream>
  #include <ostream>
  
  #include <nlohmann/json.hpp>
  
  auto main() -> int {
  std::map<std::string, std::string> map{{"key", "val"}, {"key2", "val2"}};
  nlohmann::json json{map};
  std::cout << json << '\n';  // output: [{"key":"val","key2":"val2"}]
  map = json;                 // exception: [json.exception.type_error.302] type must be object, but is array
  }

• copy initialization demo

  #include <iostream>
  #include <ostream>
  
  #include <nlohmann/json.hpp>
  
  auto main() -> int {
  std::map<std::string, std::string> map{{"key", "val"}, {"key2", "val2"}};
  nlohmann::json json(map);
  std::cout << json << '\n';  // output: {"key":"val","key2":"val2"}
  map = json;                 // ok
  }

I think this behaviour is easy to make mistakes, so probably not an intentional design.

Reproduction steps

refer to description

Expected vs. actual results

The direct initialization code should behave as the same as the copy initialization one, which enables converting json back to std::map.

Minimal code example

No response

Error messages

No response

Compiler and operating system

x86-64 clang (trunk), x86-64 gcc (trunk)

Library version

35c0b3e54ce99716bf2a6bb6bdbd346f3e6d398b

Validation

• [X] The bug also occurs if the latest version from the develop branch is used.
• [X] I can successfully compile and run the unit tests.

[gregmarr]

This is the very first item in the FAQ. https://json.nlohmann.me/home/faq/

[FeignClaims]

I see, only searched in issue, sorry for the bother